Magnet



Dec. 17, 1940. A, ElSELE I 2,224,954

MAGNET Filed April 7, 1937 2 Sheets-Sheet l qgl llmm I NVENTOR.

BY Vwm* ATTORNEYS.

ALBERTZMELE Dec. 17, 1940. A EISELE 2,224,954

MAGNET Filed April 7, 1937 2 Sheets-Sheet 2 INVENTOR. fi'zafgri'zsasATTORNEYS,

Patented Dec. 17, 1940 UNITED STATES PATENT OFFICE Application April 7,1937, Serial No. 135,413 In Germany April 9, 1936 4 Claims.

This invention relates to improvements in magnets and has for aprincipal object the provision of a magnet of any desired shape, notnecessarily corresponding to the location of the poles.

A further object of the invention is the provision of a tachometerhaving a rotor comprised of an annulus having a plurality of magneticpoles imparted thereto, said poles being distributed about said annulusthereby distributing 10 the pull equally about said rotor.

.Heretofore in such tachometers it has been customary to construct therotor of a bar magnet formed into a ring with a gap between the endsthereof. This gap, when the ring was 15 magnetized, formed a north and asouth ma netic pole andas this was rotated the pull due to currentinduced in the cooperating member was all on one side.

With the new and improved annulus having,

20 for example, four poles magnetically formed therein, the pull isequally distributed about the rotor.

Another object of the invention is the provision of an annulus formed ofcoercitive mate- 25 rial having magnetically impressed therein aplurality of poles, and the utilization of said annulus as the rotor iorelectric motors, particularly in synchronous types of motors.

Still another object of the invention is the pro- 30 vision of acylindrical magnet formed of highly coercitive material and forming asource of magneto-motive force for magnetos.

Still another object of the invention is the provision of magnetoesemloying cylindrical mag- 35 nets of the kind stated, having a pluralityof poles magnetically formed therein and having an armature with poleshoes spanning diametrically opposite magnetic poles, other polesfalling between the poles being spanned, thereby eliminating thenecessity of driving the distributor at a speed other than that of thearmature.

Still another object of the invention is the provision of a magnetohaving a cylindrical magnet wtih a plurality of invisible polesmagnetically impressed therein and forming a rotor.

Other objects and advantages or the invention will be apparent to thoseskilled in the art.

Referring to the drawings, Figure 1 is a sectional elevation of atachometer employing my new improved magnet.

Figure 2 is a plan view taken along the line 2-2 of Figure 1 with thearmature omitted.

Figure 3 is a fragmentary sectional elevation 55 similar to Figure 1with the exception that the outside inductor ring is stationary and islaminated.

Figure 4 is similar to Figure 3 with the exception that the inductorring is carried on the shaft with the magnet and rotates therewith.

Figure 5 is an isometric view of the usual type of magnet employed intachometers.

' Figure 6 is an isometric view of the new and improved annular magnet,after the same has been magnetized, the path of the magnetic flux beingindicated by dot-dash lines.

Figure 7 is a view of an synchronous clock motor employing one of thenew and improved annular magnets as an armature.

Figure 8 is an end view of one of the new and improved magnets asapplied to a magneto, the magneto armature being shown in section.

Figure 9 is a diagrammatic representation of the magneto circuitsshowing the primary and the associated interrupter and the secondary andits associated distributor.

Figure 10 is a view showing one of the new and improved magnets as arotor and showing the stationary armature pole shoes and windings insection.

Figure 11 is a sectional view showing an ar rangement of two molded diskmagnets rotatably mounted adjacent to each other with a non-ferrous wallor diaphragm therebetween.

Figure 12 is a view of one form of molded magnet suitable for use inelectrical meters, showing threaded inserts molded in, and

Figure 13 is a fragmentary sectional elevation, similar to'Figure 4,except that the outside inductor ring is molded of magnetic material.

Referring now to Figure 5 an existent form of tachometer magnet I0 isillustrated. This magnet is iormed of a bar of magnet steel and the endsII and I2 thereof are spaced apart from each other forming therebetweena gap 13. When 40 this magnet is magnetized the end Il may for examplebe of north or N polarity and the end l2 may be oi a south or Spolarity. The disadvantages of this type of magnet are:

1. That it gradually loses magnetic strength,

and

2. It exerts its pull only within an area adja cent the gap ll.

Figure 6 illustrates the new and improved magnet which is made in theform of an annulus. The composition from which this magnet is made mayconsist oiflnely divided highly coercitive steel, and a suitable binderor other means may be employed for holding such particles together. Thecomposition may be varied in accordance with the use to which the magnetmay be put, for example, it may contain particles of cobalt, nickeland/or other non-ferrous materials. No gaps are formed in the annulusand any number of poles may be magnetically formed therein. For example,in Figure 6 the series of dot dash lines indicate four magnetic polestwo north poles and two south poles. It has been found that an annulusso formed and magnetized remains, after suitable aging, unchanging 'asto magnetic strength and as to the locations of the magnetic polesformed therein.

Figure 1 shows the application of an annulus I4 such as is shown inFigure 6 as the motivating member of a tachometer. The annulus I4 issecured to the upper end of a shaft I 5, which is suitably journaled ina boss I6 integral with a housing I1. The annulus I4 members up againsta shoulder I8 and is secured to the shaft I5 by means of a nut I9. Theupper end of the shaft I5 has formed therein a counterbored depression,29, carrying a jewel or other suitable pivot hearing 2 I.

A partition 22 which may also form a dial for.

the tachometer carries a pivot bearing 23 preferably in verticalalignments with the pivot bearing 2|. A needle shaft 24 is pivotallymounted in the bearings H and 23 and carrying a needle 25 which extendsthrough an arcuate slot 26 formed in the partition 22. A suitable hairspring 21 has one end thereof connected to the shaft 24 and the otherend to a bracket 28 carried on the underside of the partition 22.

The shaft 24 also carries a cup shaped member 29 which embraces theannulus I4. This cup .shaped member may be made of copper, aluminum orany other suitable non-ferrous mate- .rial so that eddy currents inducedtherein by the lines of force of the annulus will cause the shaft 24 tobe rotated and the needle 25 to be moved over the square on the uppersurface of the partition 22 against the tension of the hair springs 21,the amount of movement in accordance with .the speed at which theannulus is rotated.

To form a return path of the magnetic lines of force a soft iron ring 39is provided. This ring has a hole formed therein of such diameter as toallow suitable clearance for the walls of the cup shaped member 29. Thering 39 may be provided with threads 3| which match threads 32 formed ina suitable supporting member 33 which of the threads 3I and 32 theheight of the ring 39 relative to the annulus I4 may be adjusted to apoint where the best results are obtained. The

supporting member 33 may be secured to the housing I1 by screws, notshown, passing through holes 34 shown in Figure 2.

In Fig. 3' the annulus I4 is mounted in the same relation to the cupshaped member 29 as that shown in Figure 1. However in place of thesolid soft iron ring 39 it may be desirable, especially on devicesoperating at high speed, to laminate the material forming the return.path for the flux due to the fact that the hysteresis might causeexcessive heating of a solid ring. In Figure 3 the ringforming thereturn path for the flux, designated by the numeral 35 is formed of astack of laminations held together by an outer ring 36. The outer ring36 may have threads 31 formed thereon matching threads 39 a in asupporting member 39, so that the laminated ring 35 may be adjustedrelative to the annulus I4.

In the'modification shownin Figure 4, the annulus I4 may be in the samerelation to the cup shaped member 29 as that shown in Figures 1 and 3.However, the soft steel or iron ring 49 forming the return path for themagnetic flux is arranged to rotate with the annulus I4 thereby makingthe lines of force out the walls of the cup shaped member 29 in asharperand more pronounced manner which is inducive to better results. The ring49 may be threaded onto a brass or other non-ferrous metal disk 4I. disk4| may be provided with a hub 42 and bored out to fit the steppedportion 43 of the shaft I5. The annulus I4 and the disk H are togetherclamped against the shoulder 44 of the shaft I5 by meansv of the nut I3.With this arrangement it is unnecessary to laminate the ring 49 due tothe fact that the path of the magnetic flux does not change with thepolarity as it does in the other arrangements shown or in the devices ofthe prior art. A further modification illustrated in Figure 13contemplates substituting for the ring 49 in Figure 4, a secondaryannulus N4 of highlycoercitive steel similar to the annulus I4a,magnetized and having its poles preferably in opposite relation to thepoles of the annulus I4a; for example where a north pole appears on theannulus I4a, a south pole would appear in the ring H4, in which case thepull on the cup-shaped member would be much greater than is the case inFigure 4, where the ring 49 is employed using soft iron or steel. Asmany poles may be impressed in the ring Na and opposite poles in thering II4 as desired. It must-be understood, however, that I am notlimited to the placing of opposite poles in line with each other as justdescribed. For example, where a northpole appears in the annulus I4a, anorth pole could likewise appear in the ring H4, in which case the linesof force would buck each other. However, when the annulus and ring arerotated, these lines of force will cut the walls of the cup and induceeddy currents therein.

In the modification showndn Figure 7, which may represent electricalmotors, particularly small synchronous motors, an annulus 45 maybeprovided with a hub 46, a suitable web 41 serving to connect the hub tothe annulus, forming an armature for the motor. A shaft 43 forms asupport for the annulus inv concentric relation to the poles 49, 49a,59, 59a, 5|, Ma, 52, 52a. A suitable ring 53 may be positioned be.-'tween the annulus and the poles of the motor. Where the ring is used,insome cases, it may be of hardened steel and magnetized, and in othercases it may be constructed of soft iron or, steel and may be eithersolid or laminated. The poles 49, 49a, and 59, 59a, are excited by acoil 54 wound on the core 55 and likewise the poles 5|, 5Ia and 52, 52a,may be excited by a coil 56 carried on a core 51. The poles 49a, 59a,5Ia, and 52a, are

embraced by closed conductors 58 which cause displaced by the lag abovementioned. When the new and approved annulus 45 is placed in thiscombined rotating field it forms a rotating armature.

The

In the modification shown in Figure 8, the anby the numeral 68, southpole by the numeral 6|,

a second north pole as 62, a second south pole as 63, a third north poleas 64, and a third south pole as 65. An armature 66 which may be of theusual H type has pole shoes 61 and 68 and a core 68 carrying thewindings. The primary winding 18 is wound next to the core and thesecondary winding II is wound on top of the primary winding, a suitableinsulation being provided between and about the windings.

It will be noted that the shoe 61 is under the influence of the northpole 68 and the shoe 68 is under the influence of the south pole 63. Thepoles 6|, 62, 64 and 65 are not influencing the armature. Therefore whenthe shoes 61 and 68 respectively break from the influence of the poles68 and 63 respectively and at the same time the interrupter 12 opens, aspark will be induced in the secondary winding II.

The magneto having poles as shown in Fig. 8 would not have to have thedistributor geared down slower than the speed of the armature. Infact'the distributor rotor could be carried by the armature and directlyconnected to the secondary winding, in which case six sparks would bedistributed during each revolution of the armature. This is showndiagrammatically in Figure 9, the distributor rotor being indicated bythe numeral 13 and 'the distributor contacts as I4 to 18 inclusive.

In Fig. 9 the interrupter 12 may consist of a lever 88 carrying acontact 8I, a bumper 82 and may be pivoted on a suitable grounded pivot83. An insulated anvil 85 may carry a suitable contact point 86 incooperative relation with the contact 8|. A condenser 81 is connected inparallel with the contact points 8| and 86. A suitable cam 84 carried bythe armature acts against the bumper 82, thereby opening the contacts Mand 86 six times during each revolution of the armature.

In the modification shown in Fig. 10, an annulus 88 made in the form ofa cylinder is 1'0- tatively mounted. It may have any desired number ofpoles magnetically impressed therein, for example, four poles namely, anorth pole 88, a south pole 88, a north pole 8| and a south pole 82.Since the magnetic cylinder 88 is rotatively mounted the armature mayremain stationary. This armature may consist of pole shoes 83 and 84respectively, under the influence of poles 88 and 82 in the relativepositions shown in the figure.

These shoes may be secured to a laminated yoke 85 in any suitablemanner, for example, by means of a screw 86. The yoke 85 may carry aprimary winding 81 having a secondary winding 88 positioned thereabout,the primary and the secondary being adequately insulated from each otherand from the yoke 85.

As the cylinder 88 is rotated, for example, in the direction of thearrow, a suitable interrupter, not shown being provided, four sparkswill be generated by the winding for each revolution of the annulus 88.Therefore if the cylinder 88 has rotating therewith a distributionrotor, it will fillnish sparks suitable for firing a four cylinder gasengine without the necessity of gearing the distributor down to slowerspeed than that of the cylinder 88.

In Figure 11 two molded magnets 88 and I88 may be employed. Thesemagnets may have molded in suitable bushings IM and I82 respectively andthe bushings may form forced fits on the shafts I83 and I84respectively, the magnet 88 being secured to the shaft I83 by suitableta- 5 per pin I85 and the magnet I88 is secured to the shaft I84 by asimilar taper pin I86. The shaft I83 is joumaled in asuitable bearingI81 and the shaft I84 is Journaled in a bearing I88. A diaphragm I88which may form a portion of the 1 wall of the casing enclosing one ofthe magnets is positioned in an air gap between the magnet 88 and I88,and is preferably constructed of nonferrous material.

' Assuming that the magnet I88 is positioned 1 within a hermeticallysealed casing and driven by a motor therein, the magnet 88, due to thefact that both of the magnets are magnetized, will be pulled around bythe flux thereby causing the shaft I83 to rotate in unison with therotation of the shaft I84. Other variations of this embodimentcontemplate the movement of a magnet outside the casing in unison withthe movement of the magnet inside the casing regardless of whether themagnets are rotated or are moved 28 laterally.

Figure 12 is a view of one form of moulded magnet for use in electricalmeters, comprising a substantially U-shaped body II8 having pole shoesII I, II2, formed integral therewith and of 8 the same material. Aplurality of inserts'II3 positioned adjacent to the pole shoes areprovided for securing end plates (not shown) which in turn supportmoving parts of the meter (not shown). These bushings may be threadedbefore being moulded in or they may be tapped after the magnet has beenmoulded.

The provision of a magnet of this kind for meters eliminates entirelyall machine work on the magnet, especially in cases where the bushingsare pre-tapped.

Although I have illustrated and described several forms and applicationsof my new and improved molded magnet some of which are in the form of anannulus, a cylinder or a disk, it is obvious that molded magnetsaccording to my invention can be constructed in other shapes for use inall kinds of electrical meters, telephones, head sets, loud speakers,etc., without departing from the spirit of the invention as defined in.the 58 following claims.

What is claimed is:

1. In a tachometer employing a magnetic annulus formed of highlycoercitive steel particles and a binder molded under pressure and havinga plurality of alternate magnetic poles impressed therein, a shaftrotatively supporting said annulus, an inductor embracing the outerperiphery of said annulus, a pivot shaft supporting said inductor, astationary annulus concentric with said 6 first annulus and at leastpartially embracing the perimeter of said inductor, said second annulusbeing adjustably axially, a pointer carried on said pivot shaft, a scalein cooperative relation with said pointer, and spring means tending touge said pointer against the direction of rotation of said first shaft.

2. In a tachometer, a magnetic annulus formed of highly coercitivesteele particles and a binder molded under pressure and having magneticpoles 7 impressed therein after molding, a casing, a shaft joumaled insaid casing and rotatively supporting said annulus, an inductorembracing the-outer periphery of said annulus, a pivot shaft supportingsaid inductor, a second annulus supported in 7 said casing in concentricrelation with said first annulus and at least partially embracing theperimeter of said inductor said second annulus being formed of solidferrous material, a pointer carried on said pivot shaft, a scale incooperating relation with said pointer, and spring means tending to urgesaid pointer against the direction of rotation of said first shaft.

3. In a tachometer, a magnetic annulus formed of highly coercitive steelparticles and a binder ofsaid first shaft, said second annulus beingadapted to be adjusted relative to said inductor and said first annulusto regulate the amount said second annulus embraces said inductor.

4. In a tachometer, a casing, a shaft rotatively mounted in said casing,an inductor including a rim inconcentric relation to said shaft, a pivotshaft supporting said inductor, a pointer carried on said pivot shaft,2. scale in cooperative relation with said pointer, spring means tendingto I urge said pointeragainst the direction of rotation of said firstshaft, and a rotor carried on said first shaft comprised of a pair ofconcentric annulae spaced apart from each other, the thiclzness of saidrim plus clearance whereby said in- I ductor may be positioned betweenand'in concentric relation with said annulae at least one of saidannulae being formed of highly coercitive steel particles and a bindermolded under pressure, and

the rim thereof having a plurality of invisible 1 magnetic polesimpressed therein after said annulus has been molded.

ALBERT EISELE.

